Blue tits have long been one of the most familiar garden birds in Britain, swinging acrobatically from feeders and breaking into doorstep milk bottles.
But now the blue tit is slipping away from garden feeders in the face of changes to the way people feed birds and competition from newer arrivals, the British Trust for Ornithology (BTO) said yesterday.
The BTO’s garden bird feeding survey, which records birds visiting feeders in 250 rural and urban gardens across the UK during the winter months, revealed a 42 per cent decline in blue tits in gardens over the past 40 years.
Other data suggest early signs of falls in the broader population of blue tits, but nothing on the scale of the reduction seen visiting feeders in gardens over the 40 years of the survey, the BTO’s Tim Harrison said.
He said the gentle, steady decline in blue tit numbers – which has seen the average weekly count per garden fall from 5.3 individuals in the winter of 1970-71 to 3.1 last winter – was “surprising”.
The habits of householders in feeding the birds had changed over the past 40 years, he said, with bird-feeding now a multi-million-pound industry.
Changes in the types of feeders provided and new foods such as nyjer seeds and sunflower hearts have seen the numbers of species such as goldfinch and long-tailed tits visiting gardens soar.
Long-tailed tit numbers have increased tenfold, while 25 times more goldfinches are being seen in gardens than visited 20 years ago.
Mr Harrison said: “In the earlier years of the survey, if you look at the food and a lot of the feeders provided – suspended monkey nuts, coconut shells, yoghurt pots – one species you could think of really tucking into these feeders is blue tits.
“They are very acrobatic and happy feeding upside down.”
He also said they were “ingenious” and naturally resourceful in finding food, for example in the way they learned to tap through milk bottle tops to access cream.
Blue tits would once have had a “monopoly” on some garden feeders, but the range of foods and feeders now put out by householders had encouraged other types of birds to visit gardens.
As a result blue tits, which are a relatively small garden bird, were having to compete with other species for their food.
“With the diversification of food and feeders, the diversity of birds has increased, and blue tits are one of those species that are feeling the pinch a bit,” he said.
Other species which have seen their numbers fall in the survey include starlings and song thrushes, which have both fallen by three-quarters, and house sparrows, which are down by 70 per cent over the 40 years of the survey.
The declines in these three species visiting garden feeders mirror large-scale falls in numbers in their wider populations.